I have this underlying, crippling fear

I have this underlying, crippling fear of the people I love dying. As soon as I get close to someone, I am plagued with nightmares about attending their funerals; I stay up all night wondering how I would ever manage to live without them, what would happen if they were ripped away from me, whether I would be able to cope.I think of ways to try to save my loved ones from perils that will likely never befall them - but how can I be sure? How can we take the risk of loving someone so easily, when it could all slip away in a second and leave us with nothing more than a collection of photographs and their ashes on our mantelpiece?